User manual - METER SUR-457
6.
PRINCIPLE OF OPERATION
After turning the power supply on, device ID and software version are showed on the
display, next the controller goes to the measurement mode.
6.1.
MEASUREMENT MODE
In the measure mode, the measurement results, converted over selected characteristic,
are displayed on the LED display. The measurement range equal to the nominal range is
called:
nominal measurement range,
and the measurement range equal to the extended
nominal range is called:
permissible measurement range
(Figure 6.1, 6.2).
For temperature inputs (TC and RTD) there is linear characteristic available only.
For this kind of inputs
nominal measurement range,
and
permissible
measurement range
are the same (no range extension available, Figure 6.3).
Figure 6.1. Definitions of measurement ranges in mode 4 ÷ 20mA
If the result of measurement exceeds the
permissible measurement range
, warning
”-Hi-”
or
”-Lo-”
is displayed rather than input signal,
depending on exceeded value (see
description of
“Lo r”
and
“Hi r”
parameters, paragraph
”inPt” menu
). The warning can be
effect of measurement circuit malfunction. In that case
“-Lo-”
means shortcut and
“-Hi-”
means break of measurement circuit. If sensor failure will be detected (e.g. broken wires), then
”S.Err”
warning will be displayed.
Figure 6.2. Definitions of measurement ranges in mode 0 ÷ 150mV
If the measurement value do not exceeds
permissible measurement range
but
displayed value exceeds range -999 ÷ 9999, the warning ”
-Ov-
” is displayed rather
than the calculated result.
20
i
”
Lo r
” parameter
”
Hi r
” parameter
4 mA
20 mA
permissible measurement range
nominal measurement range
”
Hi r
” parameter
0 mV
150 mV
permissible measurement range
nominal measurement range
i
